Coffee maker thermostatic control means



Nov. 11, 1941. M. IRELAND COFFEE MAKER THERMOSTATIC CONTROL MEANS Filed June 6, 1940 2 Sheets-Sheet l INVENTOR NURRA y [Ha AND BY ATTORNEY Nov. 11, 1941. M. IRELAND 7 COFFEE MAKER THERMOSTATIC CONTROL MEANS Filed June 6, 1940 2 Sheets-Sheet 2 53 B Y-S 7 7 85 6/ 93 NIH 7 ma 59 J7 INVENTOR NURRA yfiea AND A TTBR/VEY Patented Nov. 11, 1941 2,262,286 COFFEE MAKER 'rnEnMos'rA'ric CONTROL MEANS Murray Ireland, near Elgin, 111., assignor to McGraw Electric Company, Elgin, Ill., a corporatlon of Illinois Application June 6, 1.40, Serial No. 339,047 Claims. (Cl. 200-438) My invention relates to electric vacuum type coffee makers and particularly to temperature control and timing means therefor.

An object of my invention isto provide arelatively simple thermally actuable switch for controlling the operation of making'coiiee in a vacuum type coffee maker.

Another object of,my invention is to provide a thermally controlled switch for use on a coiiee maker, that shall cause initial heating of the water to near the boiling point and that shall thereafter maintain the coflee brew at a predetermined lower temperature.

Another object of my'invention is to provide a thermostatic switch'that shall be operable at a relatively high temperature and then at a lower temperature and that shall cause all parts to return to their initial normal positions after each use thereof.

Other objects of my invention will either be apparent from a description of one form of device embodying my invention or will be pointed out in the course of such description and more definitely set forth in the appended claims.

In the drawings:

Figure l is a vertical sectional view of a vacuum type coffee maker shown as being ready for starting a brewing operation,

Fig. 2 is a vertical sectional view similar to Fig. 1 but showing the conditions when the water has been forced from the lower container into the upper steeping container,

Fig. 3 is a vertical sectional view through the lower container shown as ready for serving coffee therefrom.

- Fig. 4 is a top plan view of the parts shown in Fig. 1,

Fig. 5 is a vertical sectional view through the base or lower part of the coffee maker with the Ports of. the thermostatic control means shown in the positions they will occupy when starting a cofie'e making operation,

6 is a diagram of the electrical circuits of my improved coffee maker,

Fig. fl is a vertical sectional view taken on the line of Fig. 5,

Fig.8 is a horizontal sectional view taken on the line H of Fig. 5.

Fig. 9 is a fragmentary vertical sectional view they will occupy when maintaining the coffee brew ready for serving.

I have elected to show my improved thermostatic control means as applied to a vacuum type coiiee maker including a lower container 2| having a lifting and carrying handle 23 secured thereto and I preferably make the container 2| of metal. I do not, however, desire to be limited thereto as other materials may be used by me. The lower container includes a hollow base 25 secured therebelow and provision is made for the insertion of a connection plug 21; connected to one end of a twin conductor cord" to permit of energizing an electric heater to be referred to hereinafter.

I provide further an upper container 3| having secured thereto a handle 33 and this container is provided with a cover 35, the opening in the top of upper container 3| being substantially the same as the opening in the top of lower container 2| to permit of using the cover 35 with either of the two containers. The upper container II is adapted to receive a charge of ground coife'e 31 and a filter structure 39 of any suitable or desired kind may be employed. This filter 'may be removably mounted on and associated with a riser tube 4| which tube extends through abottom opening 43 in upper container 8|, of reduced size, so that when the water in the lower container is heated to or near the boiling point, the pressure therein wfll cause the water to be forced upwardly in a manner now well known in the art, through the tube 4| and this heated water is to be held in the upper con-- tainer to steep the grounds 31 for a predetermined length of time. A gasket I4 is positioned between the two interfltting containers. The brew can return to the lower container 2| when the same has been cooled suiiiciently to reduce the initial pressure to a partial vacuum, through one or more openings 45 in riser tube ll, small openings 45 being located Just above portio 43 of the upper container II. I may point ou re that the bottom wall 41 of the lower container is provided with a central depressed portion I! as shown in the several figures of the drawings so that the amount of water remaining in the lower container 2| will be relatively small and that substantially all of the water is forced upwardly into the upper brewing or steeping chamher in container 3| and the temperature changes similar to Fig. 5 but showing the parts in other I operating positions, and,

Fig. 10 is a view similar to Fig. 9 except the thermostatic parts are shown in the positions under certain operating conditions will be relatively quick and large whereby effective operation of the thermal controlling means to be herelnafter described maybe obtained.

7 means not particularly shown in the drawings.

A bimetal bar 55 has one of its ends secured as by means of a short machine screw 51, against the lower end of a short metallic lug 59 which may be held against the bottom surface of lower wall 41 of container 2| in any suitable or desired manner so that the lug or stud 59 will be in good heat-receiving relation with said lower wall.

I provide further a pair of switches, the first one consisting of a relatively rigid contact .bar 5| which is mounted on a member 53 which may be of electric-insulating material and which may be a part of the hollow base portion 25 herein-, before mentioned and whichis held by a short machine screw 54. The first switch includes further a resilient contact arm or bar 55 positioned below the rigid bar 5| and this bar 55 may be supported'by a bracket 61 which may be held against a vertical surface of member 53 by one of two terminal pins 59, of which two are provided, in a manner well-known in the art. The outer end of the lower contact arm 55 extends beyond the outer end of contact arm 6| and has mounted thereon an adjustable screw II which may extend through a bushing I3 suitably brazed or welded to the outer end of arm 55. Arm 55 is biased upwardly so that normally contact members on the-two arms. and 55 will be in engagement.

I provide further a second switch consisting of an upper resilient contact bar 15 which is positioned immediately above the rigid contact bar 5| and which may be held on member 53 by the machine screw 54 which servesto hold bar 5| in its proper operative position. This arm I5 is longer than arm 65. e second switch has further a lower resilient c ntact arm 19 which has an opening therein throughwhich the lug 13 may extend to permit of movement of arm 55 and of screw II and lug l3 relatively to contact bar 19. Arms 15 and. 19 are provided with contact members in); manner well known in the art, which contact members are normally in engagement with each other as shown particularly in Fig. 5 of the drawings. ther end of arm 19 is secured to bracket 51 and small machine screws or rivets 8| may hold bars I! and55 on this bracket in electrical conducting relation therewith. Contact bar 19 is so constructed and supported that it normally is in contacting engagement with contact bar. 15 and that it bends the latter away from the rigid contact bar 5|, as shown'in Fig. 5 of the drawings.

As shown in Fig. 6 of the drawings, one ofthe terminal .pins 59 is' directly connected to the g on the rigid arm 5|. The circuit through the first arms 55 and 19 while a conductor .53 connects the two arms-5| and 15 to one terminal of the electric heating element 5|, the'other terminal of which is connected by a second conductor 55 to the other terminal pin 59, all in a manner well known in the art.

A latch member 81, of substantially L -shape, has one end thereof pivotally mounted as by a pin 89 on a supporting bar "9| of channel shape ing rod 99 which is efiective also to hold a skele-' ton frame |li| against a lower peripheral edge of base member 25.

Let it be assumed that it is desired to make coffee in a coffee maker of the kind shown in the drawings, which coffee maker is equipped with the thermally actuable control means above described. It is assumed that the desired amount of water has been placed in the lower container and the proper amount of ground coffee has been placed in the upper container and the coffee maker is now energized as by connecting the twin conductor cord 29 to a suitable source of supply of electric energy. The electric heater 5| will cause heating of the water in the lower container 2| and the vapors or stem generated thereby will cause a pressure in container 2| which will force substantially all of the water therein upwardly through tube 4| into the upper container 3|. I may provide means, such as additional openings in tube 4| below the lower end of portion 43, to prevent upward movement of the water from container 2| until it has been heated 'to a relatively high temperature. It is usually desired to continue the energization of the electric heating elements of the coffee maker for a length .of time suflicient to cause proper steeping or leaching of the ground coffee, after which the electric heating element should be deenergized to-thereby cause a vacuum to be formedand poured after the upper container and the riser tube have been removed, all in a manner well known in'the art.

Referring firstto Fig. 5 of the drawings, the parts of the thermally controlled switch means are shown in their initial substantially cold position and it may be pointed out that flexing movement of heated bimetal bar 55 in a down-'- ward direction will cause engagement of a lug ture which will hereinafter be further referred to, engagement of lug I03 on bimetal bar 55 with the end of screw 1| will result in downward movement of arm '55 to-thereby disengage-the contact member thereonlwith the contact member switch is 'thereforeinterrupted but this will have no effect upon the, energization of the electric heater since current thereto will still flow through contact arms 15 and 19 and he contact members carried thereby.

Continued energization of the heater. 5| will cause further downward warping movement of bimetal bar '55 and further bending of lower contact bar 55 until finally an intermediate part of contact bar 55/will engage a lug ||I5 mounted on the upper surface of contact arm 19 intermediate its ends so that ultimately the circuit will be broken throughthe second switch comprising contact bars I! and I9, as shown, for instance, in Fig. 9 01 the drawings. I desire here to point out that it is possible to 'predetermine and adjust, either in the factory or later if desired, the diil'erence in time and temperature required to wise direction and to substantially the position 5 fi gwn in Fig. 5 oi the drawings and this tumcause interruption "of the first switch and then' I interruption of the second switch.

When the circuit has been interrupted through the heating element 5| as by final disengagement of contact bars and 18, contact bar 19 will have been turned in a clockwise direction by reason of its having been engaged by the lower contact bar 65 of the first switch, so that latch 81', which has a shouldered portion III! at its lower end, is moved into the position shown in Fig.'9 of the drawings where it ,will be effective to hold contact bar 19 in its circuitinterrupting position. It may here be pointed out that during the early part of the movement of bimetal bar 55 the upper end of lug I03, which normally and initially is .in engagement with an intermediate part of latch 89, was

moved out of engagement therewith whereby the initial bias of this latch was removed so that spring 93 could cause turning movement thereof in a clockwise direction against the outer end of contact bar 19. As has just been stated, when bar 19 has been turned far enough in a clockwise direction by the action of the bimetal baril, latch U will engage with bar I9 to hold it in its opened position.

The heating element now being completely deenergized, it and the parts heated thereby will be subject to a fall of temperature and since the temperature at which latch 81 engaged contact bar 19 is either the boiling point of water or very close thereto, the cooling lower container 2| will shortly have a vacuum created therein, in a manner well known in vacuum type cofiee makers, with the final result that the brew is drawn downwardly into the lower container.

It is desired to now maintain this brew in the lower container at a predetermined serving temperature until it is to be'used, and the cooling bimetal bar Bl will now warp in a direction opposite to that in which it warped on being heated and this will result in counterclockwise turning movement of contact bar 65 of the first switch until finally the two contact bars I and I will again engage with the result that the heating element for the cofi'ee maker is again energized and the bimetal bar will then be subjected to reheating. As soon as the bimetal bar has again been flexed downwardly a sufilcient amount by this reheating the circuit through the heating element will thereby be broken through the first switch and sequential and consecutive energization and deenergization of the heating element coincident with the closing and opening of the first switch will continue for as long as the coffee maker is connected through its twin conductor cord to a supply circuit.

Let it now be assumed that the connection 0! the electric heater to a supply circuit is interrupted as by removing the plug from the supply circuit socket ,or by removing the plug 21 irom thecoflee maker to permit of carrying the lower container and the cover 35 thereon. to

a place of use, such as a breakfast or dinner table. It is evident that under these conditions movement may be limited by any suitable stop means. It is thus evident that the thermally controlled plural switch structure is returned to its initial, ready-to-operate condition in due course after the termination of its use in making and serving coilee. I wish to here point out that while the higher predetermined temperature is substantially that of boiling or slightly therebelow, the temperature maintained in the brewed coffee by the first switch may be any desired value, say on the order of to as may be desired by the user or as may be desired in accordance with the conditions of use.

It may be noted that the structure embodying my invention is relatively simple, embodies a relatively few parts only, and that it is pos-- which lug I 03 thereof will engage screw 1| may be varied by adjustment of screw 11 and'variation in the height of lug I05 on contact bar 19 will vary the length of time between disengagement of contact bars 65 and 6| and the disengagement of contact bars 19 and 15 and hence the diflerence between the temperatures at which such disengagements occur.

While I have illustrated a specific embodi-.

ment, I do not desire .to be limited thereto and all changes and modifications clearly coming within the scope of the appended claims are to be considered as being covered thereby.

I claim as my invention:

1. A thermal switch for controlling the electric heater 01' a cofiee maker to provide a high temperature and then "a lower temperature, said switch comprising a bimetal bar, a pair of outer resilient contact bars normally closing a circuit through the heater, a rigid contact bar electrically connected to oneof said outer contact bars and a third resilient contact bar electrically connected to the other of said outer contact bars, said rigid and said third contact bar cooperating'to n'ormally close a parallel circuit through the heater, means for causing the heated bimetal bar to first operatively engage the third resilient contact bar and move it out ofcircuitciosing engagement with the rigid contact bar and then to further move the third resilient contact bar to cause it to eii'ect movement of said other outer contact bar out of circuit-closing engagement with saidone outer contact bar and means to hold said other outer contact bar in actuated position, the bimetal bar then cooling and causing engagement and disengagement oi the rigid and the -third contact bar to maintain the bimetal bar at a substantially average temperature. 1

2. A thermal 'switch for controlling the energization of the electric heateroi' a cofi'ee maker to provide first a high and then a lower temperature in the coii'ee maker, said switch comprising a bimetal bar subject to heat from the 'coflee maker, a pair of outer resilient contact bars normally in engag ment to close a circuit through said heater,- an intermediate substantially rigid uniform contact bar electrically connected with one of said outer contact bars, an intermediate thii'd first operatively engage the third resilient contact bar and move it out of circuit-closing relation with said substantially rigid contact bar and then to further move the third resilient contact bar and cause it to move the other, outer resilient contact bar out of circuit-closing relation with said one outer contact bar and detentmeans to hold the other outer resilient contact bar in its actuated position to thereby deenergize said heater and cause cooling of the bimetal bar and sequential engagement and disengagement of the third resilient contact bar and the substantially rigid contact bar to energize and deenergize the heater and maintain the coffee maker at a substantially uniform average temperature and permanent deenergization of the heater circuit causing further cooling of the bimetal bar andengagement thereof with the detent means to cause the latter to be disengaged from said other. outer resilient contact bar.

A thermal switch for controlling the current flow through the electric heater of a cofiee maker to provide first a high temperature and then a lower temperature in the coffee maker, said switch comprising a bimetal bar subject to heat from the coffee maker, a first outer resilient contact bar, a substantially rigid contact bar, a support common to both said bars, a second outer resilient contact bar, a third resilient contact bar, a second support common to said second and said third contact bar, said supports positioning said rigid contact bar and said third contact bar between said first and second outer contact bars, said outer contact bars being normally inherently biased into contact with each other to close a circuit through the heater and said third resilient contact bar being normally inherently biased into contact with said substantially rigid contact bar to close a parallel'circuit througlr the heater, said bimetal bar being efiective on energization of the heater circuit tooperatively engage said third resilient contact bar and move it out of engagement with said substantially rigid contact bar and then to further move said third resilient contact bar into operative engagement with said second outer resilient contact bar and cause it to move out of engagement with said tially uniform average temperature in the coffee maker, permanent deenergization of the heater circuit causing further cooling of the bimetal bar and engagement'thereoi with the detent means to cause the latter to be disengaged from said second outer resilient contact bar and return of the partsof the switch to initial positions,

4. A thermal switch for controlling the current flow through the electric heater of a coffee maker including a main switch to provide first a high temperature and then a lower temperature in the cofiee maker, said switch comprising two parallelconnected pairs of contact bars normally providingtwo parallel closed circuits for the heater, a bimetal bar subject to heat from the coffee maker and efiectiv on closure of said main switch to move and erg and move it to switchwpening position and to then further move said one contact bar into engagement with a contact bar of the second pair and cause its movement into switch-opening position, and-a detent means engageable by said contact bar of the second pair to hold the latter in open position, opening of the main switch causing cooling of the bimetal bar and engagement there- 'ofwith said detent means to cause release therebimetal bar subject to heat from said heater and eifective on rise of temperature to engage one of said contact arms and thereby efiect opening of said switches in sequence and detent means for holding the last opened switch in open position, said detent means being operatively engageable by said bimetal bar when it has cooled to a predetermined low temperature to cause release of the last opened switch and return to closed position.

MURRAY IRELAND.

age one contact bar of the first pair 

